1. Field of the Invention
The present invention relates to an apparatus for manufacturing semiconductor devices. More particularly, the present invention relates to an apparatus for cleaning semiconductor wafers in accordance with the Marangoni principle.
2. Description of the Related Art
When a semiconductor wafer is manufactured into integrated circuit (IC) devices, the wafer is subjected to a series of semiconductor device manufacturing processes such as photolithography, chemical or physical vapor deposition and plasma etching processes. Foreign materials, such as residual chemicals, small particles, and other contaminants, may remain on the surface of the wafer after these processes are carried out. The foreign materials must be removed from the surface of the wafer to assure the quality of the IC devices.
A wafer cleaning process may include both rinsing and drying the wafer to remove foreign materials. A silicon wafer is generally rinsed using de-ionized water. However, the de-ionized water is an aggressive solvent against silicon and will thus eventually dissolve the silicon wafer. Accordingly, the wafer must be completely dried after being rinsed with the de-ionized water.
There are a number of semiconductor wafer cleaning systems commercially available. Recently, wafer cleaning systems based on the Marangoni principle have been widely used in the art. The Marangoni principle is based on the fact that when there is a liquid region wherein two different surface tensions exist, liquid flows from the region of the lower surface tension to the region of the higher surface tension. In Marangoni principle-based wafer cleaning systems, de-ionized water is typically used to rinse the wafer, and isopropyl alcohol (IPA) is typically used to dry the deionized water. The IPA has a lower surface tension than does the de-ionized water. Examples of conventional wafer cleaning systems using the Marangoni principle are disclosed in U.S. Pat. Nos. 5,569,330, 5,807,439, 6,027,574, and 6,354,313. These systems each include a chamber to accommodate wafers, and a bubbler for generating IPA vapor.